Conjugate turbulent natural convection with thermal radiation in a vertical and inclined wall with heat sources

Abstract

This work presents an experimental and numerical study of turbulent conjugate natural convection heat transfer in a plate for vertical and inclined positions containing protruding heat sources mounted on a conductive substrate, with thermal radiation effects. Experiments were performed with seven aluminum protruding heat sources uniformly mounted over an upper substrate fiberglass plate. Insulation and a guard heater were used at the back of the substrate plate. The temperature was measured for each power input and downward inclination angle. Numerical simulations were performed to explore the effects of conductivity, upward and downward inclinations, and heater emissivity. The conjugate problem was numerically addressed for a two-dimensional model, steady-state and incompressible flow under turbulent flow conditions. The main effort was to investigate the effects of power dissipation, conductivity plate-fluid ratio, plate inclination angle, and emissivity of the heater on temperature and Nusselt number distribution. The range of the modified Rayleigh number covers the values between 9 × 105 and 1.3 × 1010. The results found that heat loss by radiation was greater than 35%, the heat transfer became less efficient as the downward angle increased, and a jump in the average Nusselt number was found for upward cases due to plume detachment. A correlation for the Nusselt number was also developed.